Heat generator

ABSTRACT

A heat generator includes a heat generating member for generating heat flow, a temperature compensating member, and a heat flow compensating circuit connected between the heat generating member and the temperature compensating member. The heat generating member includes a heat export face and a heat insulation face. The temperature compensating member includes a temperature compensating face facing the heat insulation face. The circuit is capable of controlling heat generated by a thermoelectric resistor of the temperature compensating member to cause the temperature of the temperature compensating face to be equal to the temperature of the heat insulation face which results in the heat energy of the heat flow exporting out from the heat export face of the heat generating member substantially being equal to the heat energy of the heat generated by the heat generating member.

TECHNICAL FIELD

The present invention relates to a heat generator, and particularly to aheat generator having heat flow compensation capability.

BACKGROUND

When developing new material, especially heat conduct material, it needsto measure the heat conductivity of the material. When designing a heatdissipation device for electronic devices, the designer needs to knowthe heat conductive capability of the material of the heat dissipationdevice. Precisely measuring heat conductivity of the material is the keyof the design.

In early times, the heat conductivity of a material is measured viasandwiching a specimen made of the material between a heat source and anobject with a lower temperature. The heat generated by the heat sourceflows through the specimen to the object with lower temperature. Atemperature gradient ΔT exists between two opposite ends of thespecimen. The distance between the two opposite ends of the specimen ΔXcan be measured. Assuming that all of the heat generated by the heatsource flow through the specimen, the heat energy Q of the heat flowflowing through the specimen is equal to the heat energy Q′ generated bythe heat source. The heat energy Q′ generated by the heat source iscalculated according to the equation as follows:Q′=αI²Rwherein R is the resistance value of a thermoelectric resistor embeddedin the heat source, I represents the electric current flowing throughthe thermoelectric resistor, and α is a ratio of electrical powerconverted to heat energy of the thermoelectric resistor. The heatconductivity K of the material of the specimen can be calculatedaccording to the equation as follows:K=q*ΔX/ΔT.q represents heat flow which is the rate at which heat energy Q flowsthrough the specimen per square meter, in W/m².

In the above method, the specimen firmly contact with one face of theheat source. The other faces of the heat source are heat insulated by alayer of insulation material covered thereon in order to ensure all ofthe heat generated by the heat source flow through the specimen.However, the insulation capability of the insulation material, such asalumina, is limited. Some of the heat generated by the heat source isinevitably dissipated through the other faces which do not contact thespecimen. That means, the heat energy Q of the heat flow flowing throughthe specimen is not equal to the heat energy Q′ generated by the heatsource. Thus, the value of the heat energy Q of the heat flow flowingthrough the specimen, which is predetermined to equal to the heat energyQ′ generated by the heat source, exists an inaccuracy which results inthe heat conductivity K of the material of the specimen existing aninaccuracy.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a heatgenerator which can export a predetermined heat flow precisely.

To achieve the above-mentioned object, a heat generator in accordancewith the present invention comprises a heat generating member forgenerating heat, a temperature compensating member, and a temperaturecompensating circuit connected between the heat generating member andthe temperature compensating member. The heat generating membercomprises a heat export face and a heat insulation face. The temperaturecompensating member comprises a temperature compensating face facing theheat insulation face. The circuit is capable of controlling heat energygenerated by a thermoelectric resistor of the temperature compensatingmember to cause the temperature of the temperature compensating face tobe equal to the temperature of the heat insulation face which results inthe heat energy of the heat flow exporting out from the heat export faceof the heat generating member substantially being equal to the heatenergy generated by the heat generating member.

Other objects, advantages and novel features of the present inventionwill be drawn from the following detailed description of a preferredembodiment of the present invention with attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a heat generator in accordance witha preferred embodiment of the present invention; and

FIG. 2 is a diagram showing the heat flow compensating circuit of theheat generator.

DETAIL DESCRIPTION OF A PREFERRED EMBODIMENT

Referring to FIG. 1, a heat generator in accordance with the preferredembodiment of the present invention comprises a heat generating member10 and a thermoelectric temperature compensating member 20.

The heat generating member 10 has a solid semi-spherical shape andcomprises an outer spherical face 11 and a planar bottom face 18. Eachof the spherical surface 11 and the planar bottom face 18 has a layer ofgold mounted thereon by plating for causing the spherical face 11 andthe planar face 18 to have a uniform temperature. A thermoelectricresistor 12 is embedded in the heat generating member 10 for generatinga predetermined heat flow. The heat energy Q′ generated by thethermoelectric resistor 12 is calculated according to the equation asfollows:Q′=αI²R.wherein R is the resistance value of the thermoelectric resistor 12, Irepresents the electric current flowing through the thermoelectricresistor 12, and α is a ratio of electrical power converted to heatenergy. A thermistor 14 is installed on the outer semi-spherical face 11of the heat generating member 10 for sensing the temperatuare T14 of theouter semi-spherical face 11. A thermistor 16 is installed on the planarbottom face 18 of the heat generating member 10 for sensing thetemperatuare of the planar bottom face 18.

The thermoelectric temperature compensating member 20 is a hollowsemi-sphere receiving the heat generating member 10 therein. Thethermoelectric temperature compensating member 20 comprises an innersemi-spherical face 21 having a same curvature with the outersemi-spherical face 11 of the heat generating member 10. The innersemi-spherical face 21 faces the the outer semi-spherical face 11 of theheat generating member 10 with a small gap about 100 um formedtherebetween. The thermoelectric temperature compensating member 20 isfixed to the heat generating member 10 by a plurality of screws 30 madeof heat insulating material. The thermoelectric temperature compensatingmember 20 works based on peltier effect which means a change intemperature at the junction of two different metals produced when anelectric current flows through them. A thermoelectric resistor 22 isembedded in the thermoelectric temperature compensating member 20 forgenerating an adjustable heat flow. A thermistor 24 is installed on theinner semi-spherical face 21 of the thermoelectric temperaturecompensating member 20 for sensing the temperatuare T24 of the innersemi-spherical face 21.

Referring to FIG. 2, a heat flow compensating circuit is connectedbetween the thermistor 14, the thermistor 24 and the thermoelectricresistor 22. The circuit comprises a comparision module 40, a reactivemodule 50 and a voltage control current source (VCCS) 60. The module 40is used to compare the temperature T14, T24 of the heat generatingmember 10 and thermoelectric temperature compensating member 20. If thetemperature T14 is not equal to the temperature T24 the module 40outputs a voltage signal to the reactive module 50. The reactive module50 outputs a reactive control signal to the VCCS 60. Accordingly, theVCCS 60 outputs an adjusted electric current to the thermoelectricresistor 22 thereby adjusting the heat generated by the thermoelectricresistor 22 to cause the temperature T24 of the inner semi-sphericalface 21 of the thermoelectric temperature compensating member 20 to beequal to the temperature T14 of the outer semi-spherical face 11 of theheat generating member 10. Thus, no heat flow flows through the outersemi-spherical face 11 of the heat generating member 10 and the innersemi-spherical face 21 of the thermoelectric temperature compensatingmember 20 and all of the heat generated by the heat generating member 10flow through the planar bottom face 18 of the heat generating member 10to a specimen (not shown) which is an object of detecting heatconductivity. Therefore, the heat energy Q of the heat flow flowingthrough the specimen is equal to the heat energy Q′ generated by theheat generating member 10.

In the present invention, no heat flow flows through the outersemi-spherical face 11 of the heat generating member 10 and the innersemi-spherical face 21 of the thermoelectric temperature compensatingmember 20 and all of the heat generated by the heat generating member 10flow through the planar bottom face 18 of the heat generating member 10to the specimen. So, the planar bottom face 18 of the heat generatingmember 10 is also called the heat flow export face while the outersemi-spherical face 11 of the heat generating member 10 is called theheat flow insulation face. The inner semi-spherical face 21 of thethermoelectric temperature compensating member 20 is called thetemperature compensating face.

It is understood that the invention may be embodied in other formswithout departing from the spirit thereof. Thus, the present example andembodiment is to be considered in all respects as illustrative and notrestrictive, and the invention is not to be limited to the details givenherein.

1. A heat generator comprising: a heat generating member for generatingheat, comprising a heat flow export face and a heat flow insulationface; a temperature compensating member having a temperaturecompensating face surrounding and facing the heat insulation face; andmeans for maintaining the temperature of the temperature compensatingface being equal to the one of the heat insulation face to thereby causethe heat energy of heat flow exporting out from the heat export face ofthe heat generating member to be equal to the heat energy of the heatgenerated by the heat generating member.
 2. The heat generator asclaimed in claim 1, wherein the maintaining means comprises a heat flowcompensating circuit which comprises a comparison module which iscapable of comparing the temperature of the heat insulation face and theone of the temperature compensating face, a reactive module and avoltage control current source, the reactive module being capable ofoutputing a voltage signal to the voltage control current source whenthe temperature of the temperature compensating face and the heatinsulation face is not equal to each other.
 3. The heat generator asclaimed in claim 2, wherein the temperature compensating member has athermoelectric resistor, and when the voltage control current sourcereceives the voltage signal the voltage control current source iscapable of outputing an adjusted electric current to the thermoelectricresistor thereby adjusting heat generated by the thermoelectric resistorto cause the temperature of the temperature compensating face of thetemperature compensating member to be equal to the temperature of theheat insulation face of the heat generating member.
 4. The heatgenerator as claimed in claim 3, further comprising a pair ofthermistors respectively installed on the temperature compensating faceand the heat insulation face for sensing the temperature thereof.
 5. Theheat generator as claimed in claim 1, wherein a gap exists between thetemperature compensating face and the heat insulation face.
 6. The heatgenerator as claimed in claim 5, wherein the heat generating member hasa solid semi-spherical shape and the temperature compensating member hasa hollow semi-spherical shape.
 7. A heat generator comprising: a heatgenerating member for generating heat flow, comprising a heat flowexport face and a heat flow insulation face; a temperature compensatingmember having a temperature compensating face confronting and spacedfrom the heat insulation face; and a circuit connected between the heatgenerating member and the temperature compensating member, the circuitbeing capable of controlling heat generated by the temperaturecompensating member to cause no heat flow flowing between thetemperature compensating face and the heat insulation face whereby theheat energy of the heat flow exporting out from the heat export face ofthe heat generating member is equal to the heat energy of the heatgenerated by the heat generating member.
 8. The heat generator asclaimed in claim 7, wherein the circuit comprises a comparison modulewhich is capable of comparing the temperature of the heat insulationface and that of the temperature compensating face, a reactive moduleand a voltage control current source, the reactive module being capableof outputing a voltage signal to the voltage control current source whentemperatures of the temperature compensating face and the heatinsulation face are not equal to each other.
 9. A method to provide heatto an object, comprising: providing a heat generating member forgenerating said heat provided to said object; providing a temperaturecompensating member to surround said heat generating member except aface of said heat generating member confronting with said object; andsensing temperature of said temperature compensating member andtemperature of said surrounded surfaces of said heat generating member;and adjusting temperature of said temperature compensating member so asto provide a heat transmission balance between said temperaturecompensating member and temperature of said surrounded surfaces of saidheat generating member.
 10. The method as claimed in claim 9, furthercomprising using a circuit to compare said two sensed temperatures andgenerate an electrical current to heat said temperature compensatingmember.
 11. The method as claimed in claim 9, wherein said face of saidheat generating member is planar and the other face of said heatgenerating member surrounded by said temperature compensating member isspherical.